Staffon and his wife, Carol, were going to spend the day helping ducks.

Each spring, the Cloquet, Minn., couple ventures out onto area wetlands to inspect and refurbish wood duck nesting boxes. On this morning, they would ride the four-wheeler to the Angell Pool on the Canosia Wildlife Management Area near Pike Lake. From there, they'd travel by snowshoes to inspect 13 nest boxes, preparing them for occupancy this spring.

Wood ducks are cavity nesters. The boxes are intended to supplement tree cavities that wood ducks naturally use for nests. Other duck species, especially hooded mergansers and goldeneyes, will also use nesting boxes.

Sometimes, Staffon said, opening a nesting box can offer a surprise.

"The best we found this year was two flying squirrels," Staffon said. "When I opened the box, one came flying out."

A wildlife technician in northwestern Minnesota once discovered a fisher inside a nesting box, said Chris Balzer, Department of Natural Resources area wildlife manager at Cloquet.

"You have to be careful reaching a hand in there," Balzer said.

Wood duck comeback

Wood duck populations were decimated across the continent in the late 1800s due to market hunting and habitat loss. Populations began to recover with the advent of the U.S. Migratory Bird Treaty Act of 1918 and an end to hunting. As the population continued to grow, hunting wood ducks was allowed again starting in 1942.

The use of nesting boxes dates to the 1930s, and now thousands are in place across the country. They're often built and placed by volunteers like the Staffons.

Rich Staffon, 67, used to be paid to check these boxes each spring when he held the DNR wildlife position that Balzer now holds. After he retired in 2012, he and Carol decided they would keep tending the boxes. Over several days, the Staffons will check 110 nesting boxes on 11 wetlands, all in the DNR's Cloquet work area.

At Box No. 507 at Canosia on March 3, Staffon peered inside and found shell fragments and membranes from successfully hatched eggs last spring.

"I'd say three to four hatched," he told Carol, who logged the information.

Carol has another important role in this project. She's supposed to toss Rich the throw-rope if he happens to break through the ice. That has only happened once, and Staffon got wet only to his thighs.

Each year lately, warm weather has forced the Staffons to make their rounds earlier.

"I used to do this from mid-March to mid-April," Rich said. "This year, I started in early February."

Looking inside

On they went from box to box, Staffon towing the sled across the ice. At each box, he would use his drill to remove screws that secured the roof or a side door and see what was inside. Some boxes held unhatched eggs from last spring. All of the eggs found, on this day, were hooded merganser eggs.

Nobody knows why some eggs did not hatch. Perhaps the hen abandoned the nest. And sometimes, a hen will deposit a clutch of eggs and leave, Staffon said. That's called a dump nest.

At one nest, Staffon found five unhatched eggs and the membranes of eight successfully hatched eggs.

"I'll bet this was two nests," he said. "There's a lot of stuff in here."

He removed the unhatched eggs and added some fresh wood shavings to the base of the nest box.

The ratio of nesting box use in the Cloquet area was once about one-third wood ducks to two-thirds hooded mergansers, Staffon said. But that has changed.

"Now, I seldom get a wood duck," he said.

But wood duck populations have increased in recent years, and the daily hunting limit has increased from two to three in the Mississippi Flyway. Wood ducks are often second in the bags of Minnesota hunters to mallards. Still, the DNR considers tending the boxes a worthwhile endeavor.

"We try to get volunteer groups to do it," the DNR's Balzer said. "It's fairly easy to hand off to volunteers. It's a good way to stretch our resources and free our staff for other things."

When it's time to launch

How do ducklings get out of a nesting box?

They jump.

Ducklings hatched in a nesting box typically remain in the box for only one day, Rich Staffon said. The only way in or out of the box is through a 3-inch-by-4-inch hole near the top of the box. Most boxes have a piece of screen tacked to the inside wall leading up to the hole, Staffon said. Little toenails on a duckling's webbed foot allow it to climb the screen up to the hole.

"The hen is on the ground (or on the water) outside," Staffon said. "They have a call they make. Pretty soon one (duckling) goes up to the hole and — bonsai! They know what to do."

One by one, the rest of the ducklings follow suit.

When ducks nest in tree cavities on land, the ducklings might drop 40 feet or more to the forest floor. Sometimes their falls are broken, in a good way, by the branches of smaller trees below. They often land on leaf litter on the forest floor, which cushions their fall.